Heater construction



Feb. 2, 1932. 1 E. L AwsoN HEATER CONSTRUCTION Filed June 22. 1929 Nr 1 w f Patented Feb. 2, 1932 LAWRENCE E. LAWSON, `OLE" CHICAGO, ILLINOIS, ASSIGNOR TO SAFETY IVIINING':CO1VLIEANY,

0F CHICAGO, II`[1I1\TOIS,. A-` CORPORATION HEATER CONSTRUCTION Y Application filed June 22, 1929. Serial No. 373,016.;

The present invention relates to heat producing devices and is concerned especially with such a device constructed and designed for use in connection with blasting cartridges which employ a liquefied gas or its equivalent as the blasting medium. In cartridges of this type it is essential that the gas be vapori-Zed in a substantially instantaneous manner and :tor this purpose various chemical heat producing compounds have been developed. In order to properly handle these heat producing compounds it is essential that they be embodied in some form of casing and that provision be made for conveniently igniting the same. Blasting cartridges of the type under consideration usually embody an electrode which is insulated from the body of the cartridge and between which and the cartridge body the heater unit is disposed. Thus, it is necessary to provide the heater unit with a convenient form of contact at each end for engagement with the electrode and the cartridge body respectively. The present invention is principally concerned with the structural characteristics of a heating unit for this purpose. The general construction of the type of cartridge involved is illustrated in the patent to Ferrell, I-Ielmholtz and Crawford No. 1,610,274.

It is an object of the present invention to provide a heater unit of the character indicated which will be elicient and reliable and reasonably economical in the cost of manufacture.

Another object of the invention is to provide a heater structure of such design as to facilitate the filling or charging thereof with the heat producing compound and to eectively seal the same against leakage of the compounds.

A further object is to provide a heater construction o such design as to substantially eliminate, or, at least, minimize the possibility of short circuiting the heater.

One of the more speciic objects of the invention is to provide a heating unit which is adapted to be electrically energized and wherein the end closures of the unit form contacts for the electrical energizing means.

In the drawings, Figure l is a view in side e'leivationot a complete heater unit'.v v

AFigure 2 isa view in;longitudinalseetion showing the heater in assembled condition. Fig-ure 3l isa view sinri-lar'toFigure 2"With the end closures I displaced' outwardly-to l illustrate the methodefassemb'l'y, and o Figure 4 is a l transverse section taker-ry on line -llrof- Figure12.- l v Referring to the `drawings and particularly to Figures-2 andi' it will be observed vt-lat the improved 'heater unit comprises -v ai. *sub'stanh tially cylindrical casinglwhich 'is'formed of anonmetallicland 'preferably areadilyl comL bustible material, pa'ifr of endclosu-res 2 Vand 3 and an electric squib or matelihe'ad5'.4 The closures 2 and5 3 are formed ofmetaland 'are preferably,identicalfinsliape although slight? ly different insize, and tliediference-insize being such as tov accom'modatetheclosure-elL mentV 3 within the end of' tube'l,` 'While-the Aclosure element 2f extendover the opposite end of thetub'e. Al suitableconductor 4: ha-v'- ing the squib -or lmatcliliead arranged intermediate its ends has itsoppositeendlsoldered or; other" wise electrically' connected" t'o' the closures 2f andy 3 'respectively.y v

rl-he conductor @is sor-proportionedl with reference to the lengtliof-"the casingjas'to permit one or. both of the end closures'torb'e removed from ,the casing.` In ordinarypractice, the .closure 3 isl inserted? within tleend off the tube and gluedf inplace `and"'tlien'tlie closure .2y is removed and'turned laterally lin order to leave' the' corresponding en'diiov the casing unobstructed A'so that the-casing' may be oonvenientlyifilledfwitlrthe lieatiproducing compound;` Lei-tten filling: the ca'siiig5-ptlie closure cap? 2f is fplaced'over the end-l olf-"fthe cas-ing andi's gluedor otherwise-permanently secured in place, thus eectively sealingft'lie casing.Y v p f rIheheat'producingfcompound per sef'orms no` part of tliepresent vinvention and'is'theretore -not disclosed althouglranumber osuitable Amixtures have `been vdeveloped l' for 5this purpose l It iis fnoted,however,; tliat"=a "heat'er unitfoi `1 given3 Vdimensions is adaptable to Ya variety of working conditionsin"viewoftlie 190 fact that any desired quantity oit the heat producing mixtures Within the limits `oit the capacity of the casing may be used, such portion of the casing as may be left unfilled by the mixture being filled With a suitable inert material such as fullers earth. rlhe reference character 6 of Figure 2 indicates such an inert filling material. Y

YIt will be noted that one of the metallic closure elements is concealed Whereas the `other is exposed, the purpose'of this arrangement being to prevent possible short circuits by the contact of a metal object With the terminals or closures at the opposite ends of the heater casing. 'lhis'is of particular imi portance in the use of these heaters in metallic blasting cartridges inasmuch as it often happens that these heaters are so displaced from their normal position as to come into contact With the body of thevcartridge, thus giving rise tothe possibility of a short circuit' and hence failure of the cartridge to do its Work.l rlChe arrangement shown in quite ellective in preventing accidental short circuiting of the heater in this or any similar manner. Y l

ln practice the present heater construction is used by placing the internal closure 3 over the end of an electrode provided Within the blasting cartridge and insulated from the cartridge body and arranging the opposite closure 2 in contact With a portion of the cartridge body or element in electrical contact therewith. In this Way a circuit lis completed :from` the electrode through lthe heater unit and back tothe cartridgejcasing and in order to energize the heater unit it is only necessary to connect the electrode and cartridge casing vvith asuitable source of electricity. l

It Will be apparent that some variations may be made in the specific details of the construction and -arrangement of parts and for this reason it is not intended that the present invention be limited other thanby the state of the prior art and the scope of the appended claims.

We claim:

3. A heater unit for blasting cartridges comprising a tubular casing adapted `to be lled With a heat producing compound, med tallic closures for the ends of said casing adapted to serve as electrical contacts, an igniting device Within said casing having Vleads extending toward opposite .ends ofthe June, 1929.

LAWRENCE E. LAWSON.

l. A heatingy unit comprising a substantially tubular casing adapted to receive a heat producing mixture, a metallic cup shaped closure member for eachend of said casing, one oi' said members fitting over an end ofthe casing andthe other disposed entirely Within' the other end of the casing and an electrical for one end of said casing, an exposed metallic ,closure for the other end of said casing and an electrical igniting devicevdisposed Within the casing and having electrical connection With said closures. l y 

